This invention relates to doctor blade arrangements for controlling the thickness of a layer of toner on a toner conveying member such as a development roller in an electrophotographic apparatus.
In electrophotographic apparatus such as copiers and printers in which an electrostatic image is developed by conveying a layer of toner adjacent to a surface bearing the electrostatic image it is important to provide accurate and uniform control of the thickness of the toner layer on the conveying member. In certain prior art toner layer thickness control arrangements, a flexible doctor blade extending across the width of a toner conveying member such as a development roller lightly engages the surface of the development roller to control the thickness of the toner layer. Consequently, the doctor blade which engages the toner layer must be kept straight and flat. Otherwise the thickness of the toner layer on the development roller will be uneven, resulting in poor printing quality.
In some conventional developing arrangements a doctor blade is affixed to a mounting member either directly or through a mounting plate by several screws. This has the disadvantages of requiring one or more mounting plates and several screws for fastening the doctor blade on the mounting member and of causing distortion of the doctor blade by the application of screws.
One typical prior art doctor blade mounting arrangement is shown in the Takano et al. U.S. Pat. No. 5,303,010 in which a flexible doctor blade is mounted by clamping screws to a support plate having adjustment slots and the support plate is in turn mounted by screws to mounting members. The Kobayashi et al. U.S. Pat. No. 5,006,898 also discloses a flexible doctor blade affixed to a support member by screws and the Sakaguchi U.S. Pat. No. 5,602,631 discloses a toner leveling member affixed by screws to a mount while the Sato U.S. Pat. No. 5,752,146 shows a doctor blade clamped by a support blade which is affixed by screws to a mount.